In an internally-controlled prospective study started in 1946-1947, an extensive body of data has been collected concerning the genetic, physiological, metabolic and psychological characteristics of 1337 Johns Hopkins medical students in classes graduating between 1948 and 1964. Now for the most part physicians, they have been under observation for 16 to 29 years. Follow-up information is recorded annually on subjects and parents, and death certificates are routinely obtained. Fifty-two subjects have died between the ages of 21 and 57, 17 from suicide and 35 from other causes. The interval between entering Johns Hopkins and death ranged from a few weeks to 32 years. (The classes of 1948-1950 entered before the study started). Initial data included detailed family history and background data, measurements of blood pressure and heart rate at rest and under stress (cold pressor test, exercise test, anoxemia test, smoking), cholesterol and ponderal index, Habit Survey, Family Attitude Questionnaire, Rorschach Test and Figure Drawing Test. Follow-up inquiries are made concerning the occurrence of disease and death in subjects and parents, with periodic checks on habits of smoking, coffee, alcohol, diet and exercise, career status, marital status and health of siblings. OBJECTIVES: 1. To identify the distinguishing characteristics in youth of the future suicides, and those who develop or die from mental illness, cancer, coronary heart disease or hypertension. 2. To find new approaches to the prediction of suicide and other forms of premature death, with a view to prevention. METHODS: Methods include Student's t test, multiple discriminant function analysis, factor analysis, multiple regression, and other multivariate statistical techniques. The case study method will be an important supplement to these statistical methods. BIBLIOGRAPHIC REFERENCES: Thomas, CB: What becomes of medical students: The dark side. Hopkins Med J 138: 185-195, 1976. Thomas, CB: Precursors of premature disease and death: The predictive potential of habits and family attitudes. Ann Int Med, to appear in November or December, 1976, in press.